Transcript Transport Ch. 7 section 3

Cellular
Transport
Functions of the cell membrane.
1. Provides boundary for cell
2. Selectively permeable- only
allows certain things to pass
through- “Picky”
Ex. Window screen
3. Maintains homeostasis:
balance within the cells
Relate the structure of the cell
membrane to its function.
Membrane is a lipid
bilayer
fluid-mosaic model
Phospholipids: fatty
areas that attract
(hydrophillic) and repel
(hydrophobic) water
Embedded proteins:
“bouncers”
1. Decide who goes in &
out
2. Markers for recognition
Diffusion
Osmosis Diffusion
movement of particles from high to
low concentration
High
concentration
Ex. Perfume & Body odor
OSMOSIS
movement of water from high
to low concentration.
Both
Go through bilayer
Low concentration
Do NOT require cell energy (passive
transport)
Move until equilibrium is reached
Cells in solutions.
Compare the three types of
solutions.
ISOTONIC: same strength
particles outside = particles
inside
ISO- means “equal to”
Movement into cell=
movement out of cell
•HYPOTONIC:
concentration of dissolved
substances is lower outside
cell than inside cell
•HYPO means “below
strength”
•Water will move INTO cell
causing it to swell (it always
moves to where there is more
substances)
•Cells could rupture if the cell
takes in too much water
•This increases pressure
inside of cell (TURGOR
PRESSURE)
•HYPERTONIC:
concentration of dissolved
substances is higher
outside the cell
•HYPER means “above
strength”
•Water rushes OUT of cell
causing it to shrivel (water
rushes to where there is
more substances)
•Can result in
PLASMOLYSIS in plants
which causes wilting
•FACILITATED DIFFUSION:
High
Concentration
Glucose
molecules
•type of diffusion since
movement is from high to low
concentration, but this type
goes through a protein
channel rather than bilayer.
•Also Passive Transport
•Proteins –picky “bouncers”
Low
Concentration
Protein
channel
Molecule to
be carried
ACTIVE TRANSPORT:
transport against
concentration gradient;
goes from low to high
concentration
Go through protein
channel
This requires energy to
move them into cell; ex:
Na-K pump
Low
Concentration
High
Concentration
Molecule
being carried
Energy
•Types of active transport:
•ENDOCYTOSIS: cells take
in large clumps of
substances
•Phagocytosis: “cell eating”
take in food
•Pinocytosis: “cell drinking”
take in water
•EXOCYTOSIS: cells move
substances out(exit)
ex: wastes
Summary
Diffusion & Osmosis/ high to low conc./ go in between
phospholipid spaces/ no energy= Passive transport
Facilitated Diffusion- high to low/ no energy/ goes through
protein
Active transport- low to high conc./ requires energy/ goes
through protein
Ex. Party
`
1. Air coming into a window screen
2. Someone opens the door & you walk
through (door represents protein)
3. someone goes through the back door that is
already open
*coming in=Endocytosis
going out= Exocytosis